Its talking-baby ads may be funny, but hedge-fund honcho Ken Griffin is not laughing when it comes to his investment in struggling online brokerage firm ETrade Financial Corp.

Griffin, who owns a 9.8 percent stake in the New York brokerage through his Chicago hedge fund firm Citadel, sent a scathing letter yesterday to ETrade’s CEO, Steven Freiberg, blasting him for “catastrophic losses” and demand ing the board con sider a sale of the company.

ETrade’s shares, which have tumbled 94 percent since the start of the financial cri sis, jumped on Griffin’s move, rising 14 percent, or $1.77, yesterday to $14.72. The company didn’t return a request for comment.

Griffin, who’s been on ETrade’s board since 2009, also demanded the company’s interim chairman and CEO call a special meeting of stockholders to remove two directors.

If the company fails to call the meeting by tomorrow, the unusually exercised Griffin said he will do it himself. ETrade is required to hold a special meeting if 10 percent of stockowners ask for it.

The hedgie also demanded the board hire an investment bank to advise them on their “strategic alternatives” for boosting the stock, including a sale of the company.

The moneyman, who manages an estimated $15 billion in assets, is not known for agitating boards to boost his investments, suggesting his efforts to repair ETrade from within have failed.

Griffin invested in ETrade in 2007 with a $2.5 billion cash infusion to save it from collapse amid concerns about its exposure to toxic mortgage loans. In 2009, he invested $100 million to buy stock amid concerns of a regulatory action.

Despite all the financial help, the brokerage firm has lost money every year since 2006, according to the letter.